Cordless telecommunication system with backup interoperability of cordless telecommunication applications, in particular of a gap-specific dect system

ABSTRACT

In a cordless telecommunications system with assured interoperability of cordless telecommunications applications, in particular a GAP-specific DECT system (DECT/GAP system), having a cordless base station (G-BS) and having cordless mobile parts (D-MT, G-MT, D/G-MT) which are capable of telecommunication with the cordless base station (G-BS) via a radio interface and the number of which exceeds the number of telecommunications channels which are available in parallel at the cordless base station, collective/group calls being possible while the interoperability of the cordless telecommunications applications remains ensured, mixed operation is implemented, comprising a connection-based virtual-collective/group call and a connectionless collective/group call. In this case, [lacuna] is configured in the cordless base station (G-BS), to which cordless mobile part (D-MT, G-MT, D/G-MT) a connection-based virtual-collective/group call (GAP call; connection-based call) goes and to which cordless mobile part (D-MT, G-MT, D/G-MT) a connectionless collective/group call (connectionless call) goes. To this end, the cordless base station (G-BS) has means (MIC, PGM me ) which are designed in an appropriate manner for this purpose, for controlling connections for the cordless mobile parts.

[0001] In information systems having a message transmission path between a message source and a message sink, transmitting and receiving devices are used for message processing and transmission, in which devices

[0002] 1) the message processing and message transmission may take place in a preferred transmission direction (simplex operation) or in both transmission directions (duplex operation),

[0003] 2) the message processing is analog or digital,

[0004] 3) the message transmission via the long-distance transmission path takes place without wires based on various message transmission methods, such as FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access) and/or CDMA (Code Division Multiple Access), for example in accordance with radio standards DECT, GSM, WACS or PACS, IS-54, PHS, PDC etc. (see IEEE Communications Magazine, January 1995 pages 50 to 57; D. D. Falconer et al: “Time Division Multiple Access Methods for Wireless Personal Communications”).

[0005] “Message” is a generic term which covers both the sense content (information) and the physical representation (signal). Despite a message having the same sense content—that is to say the same information—different signal forms may occur. Thus, for example, a message relating to a subject may be transmitted

[0006] (1) in the form of an image,

[0007] (2) as the spoken word,

[0008] (3) as the written word,

[0009] (4) as an encrypted word or image.

[0010] The type of transmission for (1) . . . (3) is in this case normally characterized by continuous (analog) signals, while, in the case of the type of transmission for (4), the signals are normally discontinuous (e.g. pulses, digital signals).

[0011] On the basis of this general definition of an information system, the invention relates to a cordless telecommunications system with assured interoperability of cordless telecommunications applications, in particular a GAP-specific DECT system according to the features of patent claim 1.

[0012] Cordless telecommunications systems with assured interoperability of cordless telecommunications applications are DECT systems (Digital Enhanced (previously: European) Cordless Telecommunication; see (1): Nach-richtentechnik Elektronik 42 [Telecommunications electronics] (1992, January/February), No. 1, Berlin, DE; U. Pilger: “Struktur des DECT-Standards”, [Structure of the DECT Standard], pages 23 to 29; (2): telcom report 16 (1993), Issue 1, J. H. Koch: “Digitaler Komfort für schnurlose Telekommunikation, DECT-Standard eröffnet neue Nutzungsgebiete”, [Digital convenience for cordless telecommunication, DECT Standard opens up new fields of use], pages 26 and 27; (3): Philips Telecommunication Review, Vol. 49, No. 3, September 1991; R. J. Mulder: DECT Universal Cordless Access System”, pages 68 to 73), for which a GAP Standard (Generic Access Profile; see ETI-Publication prETS 300 444, April 1995, Final Draft, ETSI, FR) has been defined and agreed in order to ensure interoperability of cordless telecommunications applications on the basis of the DECT Standard. According to the DECT Standard and on the basis of the illustration in FIG. 1, a maximum of 12 links using the TDMA/FDMA/TDD method (Time Division Multiple Access/Frequency Division Multiple Access/Time Division Duplex) may be set up in parallel to DECT mobile parts MT1 . . . MT12 at a DECT base station BS via a DECT radio interface designed for the frequency band between 1.88 and 1.90 GHz. The FIG. 12 results from a number k of time slots or telecommunications channels (k≦12) available for duplex operation of a DECT system. The links may in this case be internal and/or external. In the case of an internal link, two mobile parts registered at the base station BS, for example the mobile part MT2 and the mobile part MT3, may communicate with one another. In order to set up an external link, the base station BS is connected to a telecommunications network TKN via, for example, a telecommunications line unit TAE or a private branch exchange NStA. In the case of an external link, a mobile part, for example the mobile part MT1, can be used to communicate with a subscriber in the telecommunications network TKN, via the base station BS, the telecommunications line unit TAE or the private branch exchange NStA. If as in the case of the Gigaset 951 (Siemens cordless telephone, see telcom report 16, (1993), Issue 1, pages 26 and 27)—the base station BS has only one connection to the telecommunications line unit TAE or to the private branch exchange NStA, then only one external link can be set up. If—as in the case of the Gigaset 952 (Siemens cordless telephone; see telcom report 16, (1993), Issue 1, pages 26 and 27)—the base station BS has two connections to the telecommunications network TKN, then, in addition to the external link to the mobile part MT1, another external link is possible from a line-based telecommunications terminal TKE which is connected to the base station BS. In this case, it is also in principle feasible for a second mobile part, for example the mobile part MT12, to use the second connection for an external link, instead of the telecommunications terminal TKE. While the mobile parts MT1 . . . MT12 are operated from a battery or a rechargeable battery, the base station BS which is designed as a small cordless exchange, is connected to a mains power supply SPN via a mains interface NAG.

[0013] Based on the simple DECT system according to FIG. 1, which is preferably used for the private domain DECT system applications are now feasible, for example in the public local domain, in which a number m of mobile parts, where m>k, are connected to a base station via the DECT radio interface.

[0014] The “m” mobile parts, in which case, for example, m=20, may in this case, according to FIG. 2 comprise, for example, a number m1 of DECT mobile parts D-MT and/or a number m2 of GAP mobile parts G-MT, subject to the following condition;

m=m1+m2, in which case m1 ε N₀ where n=0,1,2, . . . and m,m2 ε N₁ where n=1,2,3, . . .

[0015] When the situation arises in such a DECT/GAP system in which a remote telecommunications subscriber signals from the telecommunications network TKN to a GAP base station G-BS (which may be designed, for example, as an antenna diversity base station) that he wishes to set up a telecommunications link to one of the mobile parts, then the GAP base station G-BS must report this to the mobile parts, D-MT, G-MT allocated to it. This reporting takes place, for example, by the mobile parts D-MT, G-MT ringing (audible indication). Alternatively, other indication forms are also possible (for example visual indication).

[0016] On the basis of the GAP Standard, it is not possible for more GAP mobile parts G-MT to ring than the number of telecommunications channels k which are available via the GAP radio interface at the GAP base station G-BS. This is due to the fact that, based on the GAP Standard, ringing at the GAP mobile part G-MT is initiated only when a link has been set up between the GAP base station G-BS and the GAP mobile part G-MT via a message defined in the GAP Standard. This is a mandatory performance or service feature in the GAP Standard, which must be supported by all GAP base stations G-BS and GAP mobile parts G-MT. This feature results in the individual GAP mobile parts G-MT allocated to the GAP base station G-BS being called more or less simultaneously (virtual-collective/group call; GAP call; connection-based call). If, in such a GAP system, the number of GAP mobile parts G-MT called is greater than the number of telecommunications channels k via the GAP radio interface available at the GAP base station G-BS (m2>k), then a maximum of one telecommunications channel is free at the GAP base station G-BS for the first “k” GAP mobile parts G-MT. No connection may be set up by the other GAP mobile parts G-MT via which ringing can be initiated.

[0017] ETSI currently define a connectionless collective/group call (collective/group ringing), but this does not comply with the GAP Standard. This means that a GAP mobile part on a base station—for example a DECT base station which uses this connectionless collective/group call—will not ring.

[0018] Based on the document Components 31 (1993), Issue 6, pages 215 to 218; S. Althammer, D. Brückmann: “Hochoptimierte IC's fur DECT-Schnurlostelefone” [Highly optimized ICs for DECT cordless telephones], FIG. 3 shows the basic circuit design of the GAP base station G-BS according to FIG. 2. This comprises a radio section FKT, a signal processing device SVE having a signal control section SST (which is designed as a time switch controller TSC with switching functions) and having a signal conversion section SUT (which is designed as a CODEC and AD/DA converter), a clock generator TG, a microcontroller MIC, a line interface LSS to the telecommunications line unit TAE or to the private branch exchange NStA, and a power supply SVG, which are connected to one another in the illustrated manner. The microcontroller MIC contains, for example, a program module PGM in order to implement the connectionless collective/group call. The principle of the method of operation of the circuit design in conjunction with the mobile parts D-MT, G-MT is comparable with that of a DECT circuit design. The principle of the method of operation of the DECT circuit design is described, for example, in the document cited above.

[0019] The object on which the invention is based is that, in a cordless telecommunications system with assured interoperability of cordless telecommunications applications, in particular a GAP-specific DECT system (DECT/GAP system), having a cordless base station and having cordless mobile parts which are capable of telecommunication with the cordless base station via a radio interface and the number of which exceeds the number of telecommunications channels which are available in parallel at the cordless base station, a collective/group call is possible, while the interoperability of the cordless telecommunications applications remains ensured.

[0020] This object is achieved by the features specified in Patent claim 1.

[0021] The idea on which the invention is based is for mixed operation of a connection-based virtual-collective/group call and a connectionless collective/group call to be implemented in a cordless telecommunications system (which processes and transmits messages—such as images, spoken words, written words, encrypted words or images) with assured interoperability of cordless telecommunications applications of the type mentioned and explained initially—for example a GAP-specific DECT system (DECT/GAP system). In this case, [lacuna] is configured in the cordless base station, to which cordless mobile part a connection-based virtual-collective/group call (GAP call; connection-based call) goes and to which cordless mobile part a connectionless collective/group call (connectionless call) goes. To this end, the cordless base station has means which are designed in an appropriate manner for this purpose, for controlling connections for the cordless mobile parts. These means comprise, for example, a microprocessor which is in the cordless base station and has a program module designed for call control.

[0022] Advantageous developments of the invention are specified in the dependent claims.

[0023] An exemplary embodiment of the invention will be explained with reference to FIG. 4.

[0024] Based on FIG. 3, FIG. 4 shows a modified circuit design of the GAP base station G-BS according to FIG. 2. Using this circuit design of the GAP base station G-BS, it is still possible to implement, on the one hand, the connectionless collective/group call intended for the DECT mobile parts D-MT and, on the other hand, the connection-based virtual-collective/group call intended for the GAP mobile parts G-MT, for the DECT mobile parts D-MT and/or GAP mobile parts G-MT allocated to the GAP base station G-BS. For this purpose, the microcontroller MIC according to FIG. 3 contains an expanded program module PGM_(me), modified from the program module PGM. This program module PGM_(me) is used to define which of the mobile parts D-MT, G-MT which are allocated to the GAP base station G-BS a connectionless collective/group call or, respectively, a connection-based virtual-collective/group call goes to. The program module PGM_(me) means that the GAP base station G-BS is designed for both call options (mixed operation).

[0025] In FIG. 2, it was assumed that identification means (implemented in the mobile parts D-MT, G-MT) for the call options of the GAP base station G-BS are respectively designed only for the call option specific to the mobile part (mono operation). However, it is also possible for, for example, a number m3 of DECT/GAP mobile parts D/G-MT to be connected by telecommunication, via the GAP interface, to the GAP base station G-BS. In terms of the identification means, these DECT/GAP mobile parts D/G-MT are designed for both call options (dual operation; mixed operation). The condition placed on the explanation relating to FIG. 2 then becomes:

m=m1+m2+m3, in which case m1,m3 ε N ₀ where n=0,1,2, . . . and m,m² ε N ₁ where n=1,2,3, . . .

[0026] The number of mobile parts G-MT, D/G-MT which understand only the connection-based virtual-collective/group call (GAP call) results from the number “k” of available telecommunications channels at the GAP base station G-BS. For a mobile part D-MT, D/G-MT which has been called via the connectionless collective/group call to receive a call, a telecommunications channel (time slot) must be available at the GAP base station G-BS. In this case, for example, a number “i” of mobile parts DMT, D/G-MT can be called via the connectionless collective/group call. As a result of the fact that at least one telecommunications channel must always be reserved for the connectionless collective/group call, a number “j” of mobile parts G-MT, D/G-MT called in accordance with the GAP Standard is less than the number of telecommunications channels (j<k). 

1. A cordless telecommunications system with assured interoperability of cordless telecommunications applications, in particular a GAP-specific DECT system, (a) having a cordless base station (G-BS) and a first number “m” of cordless mobile parts (D-MT, G-MT, D/G-MT) which are capable of telecommunication with the cordless base station (G-BS) and the number of which exceeds a second number “k” of telecommunications channels (m>k) which are available in parallel at the cordless base station (G-BS), (b) having a third number “m1” of first cordless mobile parts (D-MT) which respond and react to connectionless call messages, (c) having a fourth number “m2” of second cordless mobile parts (G-MT) which respond and react to connection-based call messages, (d) having a fifth number “m3” of third cordless mobile parts (D/G-MT) which respond and react both to connection-based call messages and to connectionless call messages, (e) the cordless base station (G-BS) having first means (MIC, PGM_(me)) for controlling connections for the cordless mobile parts (D-MT, G-MT, D/G-MT), which send a number “j” of connection-based call messages and a number “i” of connectionless call messages, and (f) the following conditions applying, (1) m=m1+m2+m3, in which case m1,m3 ε N₀ where n=0,1,2, . . . and m,m² ε N₁ where n=1,2,3, . . . (2) m²≦k-1, in which case k ε N₂ where n=2,3, . . . (3) j≦k-1, in which case k ε N₂ where n=2,3, . . .
 2. The cordless telecommunications system as claimed in claim 1 , characterized in that the number “k” of telecommunications channels to the DECT/GAP Standard available in parallel at the cordless base station (G-BS) is equal to “12”.
 3. The cordless telecommunications system as claimed in claim 1 , characterized in that the number “k” of telecommunications channels to the DECT/GAP Standard available in parallel at the cordless base station (G-BS) is equal to “6”. 